1. Field of the Invention
This invention relates to a method for rendering urea formaldehyde molding compositions more free-flowing. In particular this invention relates to the application of a polyorganosiloxane or a silane to a urea-formaldehyde resin or urea-formaldehyde resin containing molding composition whereby to render the resultant solid free-flowing urea formaldehyde composition more free-flowing. This invention also relates to a urea-formaldehyde molding composition containing an organopolysiloxane or a silane.
2. Discussion of the Prior Art
It is known that urea-formaldehyde resins, such as those used as binding agents in thermosetting, organically filled molding compositions, display, in contrast to other thermosetting resins, an incipient softening at even moderately elevated temperatures, which results in a certain stickiness in the resins. This has undesirable consequences. For example, in the automatic fabrication of granular, free-flowing urea resin molding compositions, the composition granules stick together and become lumpy under the influence of heat, even in the feed hopper of the fabricating machine, thus losing their free-flowing ability. This can cause trouble by interfering with the precise metering of the composition.
This undesirable agglomeration of the particles can also occur during the storage of the molding composition, especially at temperatures above 25.degree. C. and under heavy stacking pressures. Under such circumstances, large, strongly consolidated lumps can form, which make the composition useless for automatic fabrication.
Accordingly, it has become desirable to provide a means for rendering urea-formaldehyde resins more free-flowing. In particular, it has become desirable to provide a means by which the urea formaldehyde molding composition does not become sticky and agglomerate into lumps at elevated temperatures above 25.degree. C. such as are experienced during the summer season.